This invention relates to blood separation methods and apparatus, and more particularly to the isolation of cryoprecipitate or cryoglobulin.
Cryoprecipitate, isolated from blood plasma, is rich in clotting factors. For this reason, it has long been used for the treatment of hemophilia. More recently, it has been proposed to make a "fibrin glue" for sealing surgical joins using a multi-part mixture of cryoprecipitate, thrombin and calcium chloride. Cryoprecipitate alone has also been reported as suitable for such use, especially as a natural clotting sealant around sutured joins of arterial or venous tissue. Although of lesser tensile strength than a fibrin glue composition, approximately 2 to 3 percent of plasma may be isolated as cryoprecipitate, and the isolation may be performed in a hospital blood bank. Thus, autologous aliquots of "cryo" for surgical use may be prepared. This offers great promise in heart surgery, where suture bleeding, and patient cross reactions to blood-derived agents are both particularly grave problems.
The standard procedure for isolating cryoprecipitate uses a conventional phlebotomy set. The blood is drawn and anticoagulated, and centrifuged to separate the plasma. The plasma is expressed to the plasma bag, which is then sealed. The plasma bag is then frozen and thawed, which results in the precipitation of cryoprecipitate as a whitish factor. The cryoprecipitate is then separated from the plasma by centrifuging the plasma bag, and expressing the lighter cryo-poor fraction from the bag, leaving the cryoprecipitate fraction of 4-8 milliliters in the bag. Alternatively, the thawed plasma may be centrifuged in one or more centrifuge tubes, isolating the cryoprecipitate as a highly viscous plug in the bottom of each tube.
The separated material may be used by daubing about a surgical site with a spatula, or may be refrozen and thawed to result in a thinner, injectable form of cryoprecipitate such as used for the aforementioned treatment of hemophilia.